The present invention relates to the production of evident permanent surface markings of a prescribed pattern, such as for serializing, hall-marking, identifying and/or personalizing, on a glazed surface without the need for refiring or piercing the surface. More particularly, the invention relates to method and apparatus for guiding a pointed bondable metal writing rod through a prescribed marking pattern in contact with a moistened glazed surface with sufficient pressure and motion rate to effect an evident transfer and bonding of material from the rod to the surface in the desired pattern.
Permanent markings for such purposes have been produced on already glazed surfaces by applying conventional marking or coloring material in the desired pattern and then firing or heating such area sufficiently for bonding to occur. However, this procedure is limited by available facilities, additional cost, and the extent and manner in which such firing or heating can be effected without marring the glazed object or existing design thereon.
Without such heating, glazed surfaces are relatively impervious and resist permanent open-surface bonding by conventional inks, paints and adhesives, which can be removed by scraping, abrasives, solvents or simply washing. Markings for serializing or individualizing a glazed item may be applied prior to glazing, and thus under the glaze for permanence. However, this method does not afford the flexibility of an after-glaze marking, and presents the problem of numerous gaps in a production run of items having sequential serial numbers, for example, as a result of breakage and rejects.
Labels or markers may be affixed relatively permanently, but these may look unnatural or unseemly in comparison to a direct marking, and may be subject to removal or defacing.
It is also known to engrave markings into glazed surfaces. However, while such markings are permanent, they may not be apparent unless they are relatively deep and/or filled in with a coloring material. The resultant breaking of the glaze leaves the underlying absorbent ceramic subject to contamination and is unacceptable to most producers of glazeware.